In recent years, various apparatus which are equipped with a tuner unit for receiving digital broadcasts such as digital TV broadcasts and digital radio broadcasts, have been introduced into the market. Portable apparatus such as notebook personal computers and cell phones have come to be equipped with such a tuner unit to allow users to receive digital broadcasts via wireless transmission path even while a user is out of the door and while the user is moving.
Although capable of receiving digital broadcasts during movement, these apparatus sometimes suffer from a loss of data in a wireless transmission path. This is because broadcast waves are interrupted by an obstacle such as a building, a tree, a bridge, or a tunnel as the apparatus passes the shadow of the obstacle during the movement.
When errors occur in video data or audio data due to a loss of data, picture disorder or a sound interruption occurs in the apparatus. An uncomfortable feeling of the viewer due to picture disorder among these problems can be relieved relatively easily and effectively by, for example, maintaining a still image.
In contrast, it is difficult to reduce an uncomfortable feeling due to a sound interruption by simple processing such as mere muting.
In connection with the above, an audio decoding device is known which can suppress degradation in auditory feeling by reducing a sound interruption feeling caused by muting. An example of such device is disclosed in JP-A-7-336311. This device can reduce an uncomfortable feeling due to a sound interruption by replacing immediately preceding coding parameters with coding parameters of a past silent frame when code errors are detected in consecutive frames.
In conventional techniques as typified the one disclosed in the publication, JP-A-7-336311, attention is focused on how to compensate for, that is, whether to repair or to replace, errors in audio data. These replacement (interpolation) techniques are effective in the case where errors in audio data last only a very short time. However, when errors in audio data last long time because the apparatus receiving a broadcast enters a tunnel, managing to compensate for a silent portion may produce an unnatural sound contrary to the intention. As such, at present, the replacement techniques for compensating for a silent portion are not necessarily used effectively.